This invention relates to a multi-mode reproducing apparatus wherein in at least one of the modes of operation a marginal illumination apparatus of this invention is utilized to prevent the development of unexposed areas of a photosensitive imaging surface. The marginal illumination apparatus of this invention is particularly useful with reproducing apparatuses having the capability of providing copy images selectively at one of a plurality of magnifications. In a reduction mode of operation the copy image does not completely fill the copy sheet and the associated area of the photosensitive imaging member. If this margin of region the imaging member is not illuminated, it will develop out as a dark border which can print-out on the resulting copy sheet. In an electrostatographic system the development of the margins with toner can easily overburden the cleaning system causing cleaning failures or shortening the interval between maintenance calls.
It is, of course, known in the prior art to utilize illumination systems for erasing or discharging the photoconductive drum of an electrostatographic reproducing machine. In U.S. Pat. No. 2,927,516 to Hicks, a portion of the electrostatic image is erased in an address label printer.
U.S. Pat. Nos. 3,556,655; 3,685,894 to Lux et al. show the use of marginal illumination in association with a reproducing machine of the electrostatographic type having plural modes of operation at different copy image magnifications. In response to the selection of a reduction mode of operation the marginal illumination lamps are energized to discharge the photoconductive medium in the unimaged areas.
U.S. Patent Nos. 3,612,682 to Shelffo; 3,784,301 to Sato; 3,799,666 to Fukushima, et al., and 3,792,913 to Simmons are illustrative of the large variety of prior art systems for erasing non-image bearing margin regions of a photosensitive surface prior to development. The aforenoted systems principally utilize illumination lamps and suitably shaped shades or masks for providing the illumination necessary to erase the non-image area.
U.S. Pat. No. 3,724,942 to Gibson is illustrative of the prior art wherein shutters and utilized during fly-back of a scanning optical system for providing a high reflective surface to illuminate the inter-document areas of the photosensitive imaging member, and thereby erase the undesired non-image area between the documents.
It is also known to utilize reflective platen covers for providing illumination of the non-image areas outside an original document being copied which is smaller than the viewing platen. For example, in German OLS No. 2,364,324 to Okada, when an original smaller than the platen is copied a mask supported about the original is utilized to provide illumination of the marginal portions of the photosensitive member
In U.K. Pat. No. 1,363,751 to Albert, it is proposed to use a mask having an aperture for limiting the area of the image as well as illumination means for illuminating the border area of the photoconductive element surrounding the projected image.
It is proposed, in accordance with this invention, to use available light provided by the illumination system of the optical imaging apparatus for providing marginal illumination. Preferably, the available light rays which are utilized depart from the image ray path so as not to interfere with the normal imaging function.
A variety of electrostatographic reproducing machines are commercially employed which have different modes of operation. One type of machine utilizes a moving original exposure system wherein an original document is moved past a fixed slit optical system projecting an image onto the moving photoconductive surface. These machines include a means for changing the magnification of the projected image to provide reduction copies. Exemplary of patents in this area is U.S. Pat. Nos. 3,076,392, to Cerasani et al., and 3,649,114 to Vlach et al.
Other machines have been adapted to copy stationary original documents at a variety of magnifications or reductions through the use of a scanning optical system. Exemplary of patents in this area are U.S. Pat. Nos. 3,476,478, to Rees, Jr.; 3,542,467 to Furgeson; 3,614,222 to Post; and 3,837,743 to Amemiya. Another approach which has been utilized for projecting images for reproduction at varying magnifications from a stationary original comprises full frame exposure. Exemplary of patents in this area are U.S. Pat. Nos. 3, 543,289 to Koizumi; 3,687,544 to Muller; 3,703,334 to Knechtel; and German Offenlegungsschrift No. 2,154,944 to Libby.
U.S. Pat. Nos. 3,703,334 to Knechtel an 3,837,743 to Amemiya set forth above are also significant in that they disclose the use of a separate reflector or add reflectors, respectively, which are selectively positionable in the optical path for changing the conjugate distance of the optical system for providing varying magnifications.
The aforenoted machines are adapted to provide one or more modes of copying having different magnifications. In the optical systems of these machines, some means is usually provided for changing the conjugate relationship of the object and image sides of the projection lens. This may be accomplished by translating the lens between different positions for different projected image magnifications or in accordance with an alternative approach by utilizing more than one lens whereby different lenses are selectively positionable in the optical path, depending upon the projected image magnification desired. See, for example, U.S. Pat. No. 3,779,642 to Ogawa.
Other forms of multi-mode copiers are available commercially. For example, in the Xerox 3100 LDC machine an optical system is provided which enables the machine to copy from a stationary original in a first scanning mode or from a moving original in a second fixed optical mode. This latter mode is particularly adapted for copying documents larger than the conventional viewing platen size. U.S. Pat. No. 3,900,258 to Hoppner et al. [1] is illustrative of a machine similar in many respects to the 3100 LDC machine
Reproducing apparatuses including the capability of making copies from both moving and stationary originals are also described in U.S. Pat. No. 3,833,296 to Vola, and in IBM Technical Disclosure Bulletin, Vol. 12, No. 1, at page 173, June 1969.
It has been found desirable, to provide a multi-mode reproducing apparatus having various unique features of the 3100 LDC machine, including its extremely compact size, but also having the capability of reduction copying.
One approach to such a machine is described in U.S. application Ser. No. 588,971, filed June 20, 1975, to Hoppner et al. [2]. In that application a multi-mode reproducing apparatus is provided including both moving and stationary original exposure modes, with at least two modes of moving original exposure at differing copy image magnifications. The Hoppner et al. [2] machine includes a first optical mode wherein a stationary document is viewed and an image thereof is projected onto a moving imaging surface. In a second mode a document moving at a first speed synchronized to the speed of the moving imaging surface is viewed and an image thereof projected onto the imaging surface at a desired magnification. In a third mode a document moving at a second speed synchronized to the speed of the moving imaging surface is viewed and an image thereof projected onto the surface at a reduced magnification. In the reduction mode of operation a scanning optical system is held fixed at a given position and an additional optical element comprising an add mirror is inserted into the optical path in order to change the conjugate on the object side of the lens. The lens is also shifted to a new position to align it with a repositioned optical path.